CAUSES OF INFERTILITY IN TREES. 53 



The cause of infertility in indigenous trees can 

 arise from no defect of construction in the organs 

 of fructification, but from some obstruction, per- 

 version, redundancy, or vitiation of the natural 

 powers ; which is particularly manifested by the 

 faculty which they possess at one period of pro- 

 ducing fruit, and their impotency at another. This 

 imbecility from one cause or another probably in- 

 fluences at periods every tree or herb that springs 

 from the earth; but in regard to the oak, the most 

 general and probable cause of its sterility is sus- 

 pended circulation. This is more immediately 

 brought to notice from our custom of barking the 

 timber of this tree in the spring. At times our 

 barkers go on rapidly with their work ; yet in a 

 few hours a frost, or a sharp wind, will put an en- 

 tire'stop to their operations, in consequence of the 

 cessation of the flow of sap, which is followed by 

 the adhesion of the bark to the wood. Whenever 

 this nutriment ceases to be supplied, the immature 

 and tender germen must languish ; and if the sup- 

 ply be long suspended, it must perish from defi- 

 ciency of food. That such is the natural effect of 

 spring frosts and sudden chills, more injurious pro- 

 bably to the fruit in this immature state, from its 

 greater delicacy, than when it is more developed, is 

 reasonable to suppose : how far a change of seasons 

 may have taken place to accomplish the injury 

 alluded to, more commonly now than in former 

 periods, we have no criterion for proving ; but if 

 failures of the acorn crop took place as frequently 



